JPH02204316A - Complex of flexible graphite grain and amorphous carbon - Google Patents

Abstract

PURPOSE: To produce composites of flexible graphite particles and an amorphous carbon binder phase by pulverizing a flexible graphite molding, mixing the pulverized material with an org. binder by a specified ratio, compacting the mixture and then carbonizing the binder by heating.

CONSTITUTION: The flexible graphite molding is pulverized to obtain flexible graphite particles. The particles are mixed with an org. binder to obtain a mixture consisting of 40-99 wt.%, preferably 65-90%, particle and 1-60%, preferably 10-35%, binder. A liq. thermosetting resin, e.g. a phenolic resin, is appropriately used as the binder. The mixture is then formed into an aggregated compact. The compact is heated to a temp. at which the binder is carbonized. Consequently, a composite comprising the flexible graphite particles and an amorphous carbon phase binding the particles together and contg. preferably 1-50% amorphous carbon phase is obtained. This composite is elastic, has enough rigidity to resist the flow and migration under pressure and has resistance to chemicals and wear and heat stability.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to resilient packing materials.
Composites suitable for holding packing materials, etc., particularly those having chemical inertness, high temperature stability, and sufficient rigidity to prevent flow or migration of packing materials under pressure. Regarding.

A valve in which the moving mandrel or shaft of the invention extends through the wall of the device;
BACKGROUND OF THE INVENTION In fluid handling devices such as pumps, seals are required to prevent fluid from escaping the device. This often involves packing compressed packing material around the shaft and placing the compressed packing material in a packing box.
fHng box). The packing material should be elastic so that it deforms under compression to conform to the interior of the packing box and form an airtight seal against the axis of movement. The packing material should also present a low friction surface to the moving shaft and be stable under the environmental conditions to which it may be exposed.

It is also desirable to blow off or purify foreign matter when the shaft passes through the packing box. Therefore, along with the packing material, the packing box preferably contains a refractory material that removes foreign material from the shaft without scratching or scoring the surface.

Flexible graphite is described, for example, in U.S. Pat.
．． It has been successfully used as a packing material, as disclosed in US Pat. As used herein, the term "flexible graphite" refers to
ol IaLed) means a material consisting of graphite produced by compressing graphite flakes to form an agglomerate. Flexible graphite is preferred as a packing material because its resilience allows the shape of the packing material to match the internal dimensions of the packing box and to form a precise interference fit with the shaft, thus providing a seal. preferable. Furthermore, flexible graphite
Being essentially linear carbon, it has excellent thermal stability and chemical resistance. flexible graphite packing material
R8 is the tendency of the shaft to push into or flow into the clearance when passing through an opening in the packing box. This problem is particularly severe when the clearances are large, for example due to wear.

A solution to this problem is to provide a backing system that includes an annular end ring around the shaft when the shaft passes through the opening in the packing box. The end ring is
It should be made from a material that is rigid enough to prevent extrusion of the end ring itself, but resilient enough to form an airtight seal around the shaft. The end ring is
It functions to block or reduce the clearance between the shaft and the packing box and to prevent packing material from pushing into the clearance.

Commonly used end ring materials are braided carbon or graphite m-fiber. Although with some success, these packing materials generally contain a lubricant that is not thermally stable and evaporates upon heating, resulting in a loss of end ring capacity. This results in leakage due to loss of compression of the packing material. Furthermore, carbon and graphite m-fibers break through axial movement,
produces small particles, which are lost from the packing box,
It also tends to result in loss of end ring capacity. These small particles also cause excessive wear on the packing material, resulting in premature failure of the packing material.

It would be desirable to have a material for the end ring that is elastic so that under pressure it will conform to the internal shape of the packing box and the surface of the shaft, but still provide a stiffness that will prevent flow or extrusion. . Preferably, such material will also be wear resistant to prevent end ring wear and loss of capacity.

It is known that reinforced flexible graphite articles can be produced by pressing flexible graphite together with reinforcing materials such as wire mesh, or by laminating flexible graphite sheets to reinforcing polymer or metal sheets. It is. An example of such an article is U.S. Pat.
No. 7,491 and No. 4,234,638. However, the presence of these reinforcing agents usually degrades the chemical inertness and heat resistance of these composites. Furthermore, metal reinforcement in the end rings can score the shaft and cause excessive wear.

U.S. Pat. No. 1,137,373 describes a composition in which exfoliated graphite flakes or expanded graphite flakes are mixed with a binder to coat all exposed surfaces and individual thin layers of graphite. There is.

The mixture is then compressed and the binder is cured to form a composite consisting of individual thin layers of graphite bound together by the binder. The molded article may be carbonized by heating to red heat in contact with air.

These composites are made from exfoliated graphite but do not have the microstructure of flexible graphite. The reason is that each thin layer is surrounded by bonds ~1 and n
This is because the binder would not have similar properties and would not have improved the resilience of the flexible graphite material.

U.S. Pat. No. 4,190,257 discloses a packing material consisting of particles of flexible graphite compressed together into a backing ring. Optionally, phenolic resin or carbon fibers may be added to act as binders or reinforcements.

OBJECTS OF THE INVENTION It is therefore an object of the invention to provide a material that is elastic but sufficiently rigid to resist flow or migration under pressure.

Another object of the invention is to provide a material whose resilience and stiffness can be controlled.

Another object of the invention is to provide a material that is chemically resistant, thermally stable and exhibits a degree of resilience.

Another object of the invention is to provide a material that is harder and more wear resistant than flexible graphite.

Another object of the present invention is to provide a material which, when used as an end ring for a packing box, will not squeeze into the clearance between the shaft and the packing box and will prevent packing material from pushing into the clearance. It is about providing.

Other objectives will become apparent from the description below.

SUMMARY OF THE INVENTION One aspect of the invention consists of a composite characterized in that it includes particles of flexible graphite and an amorphous carbon phase that binds the flexible graphite particles together.

Another aspect of the invention comprises: (a) a container device disposed on the wall and around the axis and around an opening in the wall; (b) an elastic packing material disposed in the container device about the axis; c) an end ring located in the container device around the axis and adjacent to the packing material on the clearance between the axis and the edge of the opening (the end ring is made of particles of flexible graphite and flexible graphite an amorphous carbon phase that binds the particles together); and (d) compressing the end ring and packing material in the direction of the shaft centerline to conform the packing material to the interior space of the container device and the shape of the shaft for sealing. and the end ring is provided with a compression device for blocking the clearance between the shaft and the edge of the opening to prevent extrusion of packing material through the clearance. a seal suitable for preventing fluid leakage through the clearance between the axis of movement and the edge of the opening when passing through the opening.

Another aspect of the invention provides for producing a composite consisting of particles of flexible graphite and an amorphous carbon phase bonding together the particles of flexible graphite, including: (a) pulverizing a flexible graphite molding; to provide particles of flexible graphite: (b) particles of flexible graphite are mixed with an organic binder to form 40-99% by weight of flexible graphite particles and binder 1;
(c) forming the mixture into a cohesive molding; (d) heating the molding to a temperature that carbonizes the binder. .

The particles of flexible graphite are derived from flexible graphite moldings, such as the sheet material commercially available from Union Carbide Corporation of Danbury, CT under the name Graphoil (cI?AFOIL O). A flexible graphite sheet is formed as follows. Insert graphite flakes (Inter
calatlon) agent, typically a mixture of sulfuric and nitric acids, and the treated graphite flakes are exposed to temperatures typically in excess of 1000° C. to form expanded and exfoliated graphite flakes. The exfoliated graphite flakes are then pressed together without a binder, typically into a flat sheet. A more complete description of flexible graphite and methods of making it is found in US Pat. No. 3,404,061.

In the production of the composites of the invention, the flexible graphite particles are milled using conventional equipment, namely:
Obtained by pulverizing flexible graphite using a crusher, cutting knife, etc.

The flexible graphite particles are then coated with an organic binder material,
For example, when mixed with a liquid or solid thermosetting or thermoplastic resin or pitch, 40
A mixture is prepared having ~99, preferably 65-90% by weight of flexible graphite particles and 1-60, preferably 10-35% by weight of binder. The organic binder should be coke-forming to form an amorphous carbon phase. The material has a coke yield higher than 40%,
preferable.

The mixture is then formed into the desired shape by conventional techniques such as compression molding. The molded article is then subjected to a temperature sufficient to carbonize the resin and form an amorphous carbon phase.

If the organic binder is a thermosetting resin, it may optionally be cured before the carbonization step.

The amorphous carbon phase is substantially amorphous carbon formed by carbonization or coking of an organic binder. However, it is understood that the amorphous carbon phase may be partially crystalline and contain an ordered or partially graphitic molecular structure.

A preferred use of the composite of the present invention is as an end ring in a seal around the shaft of a fluid handling device where the shaft passes through an opening in the wall of the fluid handling device.

The seal of the present invention includes a containment device, such as a packing box, placed on the wall around the opening.

Packing material is placed in the containment device to surround the shaft. An end ring made of the composite of the present invention is placed around the shaft and one inch between the opening and the packing material. When compressing the end ring and stuffing material combination, the resilient stuffing material aligns with the interior space of the containment device (that space would not otherwise be occupied by the end ring) and compresses the surface of the stuffing material relative to the axis. to provide forced bearing, thereby providing a seal against fluids. Compression of the end ring blocks the clearance by bearing the inner surface of the end ring against the shaft, thereby preventing elastomeric packing material from being extruded through the clearance.

In a typical seal, the movable shaft exits the fluid handling device through a first opening, enters and passes through the container device or packing box, and exits the packing box through a second opening. The end ring of the invention preferably applies to both openings. A resilient packing material is between the end rings. The seal of FIG. 1, discussed in detail below, is representative of such a seal.

Preferably, the resilient packing material used in the seal of the present invention is a flexible graphite material, but other resilient packing materials may be used, such as asbestosrobe packing.

The composites of the present invention are particularly useful in applications requiring a resilient material with sufficient stiffness to resist seal creep or flow. As mentioned above, the preferred application is as an end ring. Additionally, other applications that benefit from the resilience and stiffness of the composites of the invention, e.g.
Thrust bearing rings in ball valves are contemplated.

The present composites of flexible graphite particles and an amorphous carbon phase are particularly useful in thermal applications or chemically corrosive environments. Since these composites are essentially elemental carbon, they have the same thermal stability and corrosion resistance as other carbon materials such as flexible graphite.

The composite of the present invention is also useful in applications requiring a bearing surface that wipes or cleans the shaft as it moves through a seal, such as in a reciprocating pump or valve. In addition to imparting stiffness to the composites of the present invention, the amorphous carbon binder phase
It provides a refractory surface that provides this cleaning action without undue wear and abrasion of the shaft material.

In the composite of the present invention, the flexible graphite particles impart resilience to the composite, but unlike flexible graphite, the composite of the present invention is more rigid, i.e. when under pressure. More resistant to extrusion and flow. Stiffness is provided by the amorphous carbon phase. However, the composite of the present invention is more elastic than amorphous carbon, which is hard, inelastic, and brittle.

DETAILED DESCRIPTION OF THE INVENTION In general, the size of the flexible graphite particles is not very critical. However, the particle size should be small enough so that the particles are substantially uniformly distributed throughout the amorphous carbon phase. Furthermore, large amounts of ultrafine particles will drastically reduce resilience. Generally, less than about 20% by weight of the particles, based on the weight of the graphite particles, will be present in 200 meshes (
Tyler) (0,074 dragons) is preferred.

The flexible graphite particles are then mixed with a binder that serves as a precursor for the amorphous carbon phase.

Preferably, the binder, when subjected to coking temperature,
Has high coke yield. Suitable binders include thermosets, thermoplastics, and pitch. Preferred binders are liquid thermosetting resins, especially phenolic-based resins.

Mixing of the flexible graphite and resin can be accomplished using any known mixing method to sufficiently disperse the binder throughout the flexible graphite particles. The binder may be in liquid or powder form. Liquids are preferred for their ease of dispersion into flexible graphite particles. Liquid binders may require a dispersant to reduce viscosity and aid dispersion. Solid or viscous binders may require some heating to liquefy the binder. Mixing should be gentle to prevent excessive abrasion of the flexible graphite particles. Suitable blenders include a 2 ciel or v-type blender, a drum blender (llobart)
Examples include mixers.

The amount of binder is selected such that in the final composite the amorphous carbon phase is uniformly distributed throughout the composite. in general,
Binder amounts of 1 to 60% by weight are suitable, but amounts greater than about 10% by weight are preferred to ensure sufficient amorphous carbon phase in the product.

For ease of handling, liquid binder materials are preferred and are preferably present in an amount sufficient to prepare a flowable powder mixture as opposed to a pasty or semi-liquid mixture. In the case of liquid phenolic binders, as used in the examples below, amounts of less than 35% ffi, based on the weight of the mixture, are suitable.

The mixture is then formed into the desired shapes.

The molding forms a cohesive molding which retains its integrity when the molding is fired to transform the binder into amorphous carbon. Molding conditions are selected depending on the binder material used.

Dispersants used in mixing should be evaporated off before molding. Thermoplastic or pitch binders may require heating of the mixture to soften or liquefy the binder material during molding.

If the binder is a thermoset resin, the molded article may optionally be heated to cure the thermoset resin. Curing of the thermoset resin may not be necessary if the molded article maintains structural integrity upon firing without pre-curing of the resin.

The article is preferably formed under sufficient pressure to achieve a density of 55 to 135 pounds per cubic foot, preferably 90 to 100 pounds per cubic foot. Carbonization generally results in some loss of density, depending in large part on the coke number of the organic binder and the amount of organic binder used in making the article. The final density of the composite after carbonization is preferably 50~
130 pounds per cubic foot, preferably 80-100
Pound/cubic foot. Generally, the lower the density, the more elastic the composite.

The resilience of the composite can be increased by lowering the content of the amorphous carbon phase by using larger particle sizes of flexible graphite or by reducing the amount of binder in the binder/flexible carbon mixture. It may be increased by

The amorphous carbon phase in the final composite generally represents 1 to 50 ffi weight percent of the composite based on the total weight. Thickening agent 10-3
In the preferred practice of the invention, where 1 m% is used in the binder/flexible carbon mixture, the amorphous carbon phase in the final composite is generally about 8-33% by weight of the composite. Generally, the compressibility of the composites of the present invention is as per ASTM F-36
It is about 5-11% when tested by the test method.

The molded article of binder and flexible carbon particles is fired to a temperature that carbonizes the binder and forms an amorphous carbon phase. The temperature is
Depending on the binder used, temperatures above 400 DEG C. are generally preferred. Generally, the binder should carbonize at the highest temperature to which the composite may be subjected. Carbonization temperature 450
C to 1000 C is suitable. Higher carbonization temperatures may be used, but may reduce the hardness of the amorphous carbon phase. Preferred degrees of hardness are achieved at carbonization temperatures of 475°C to 675°C. In the case of values for industrial applications, the carbonization temperature is preferably between 500<0>C and .600<0>C. The rate of temperature rise should be slow enough to prevent structural defects in the final product due to thermal stress.

As mentioned above, a preferred use of the composite of the present invention is as an end ring. The figure is a simplified cross-sectional view of a seal of the present invention using two end rings. Reciprocating shaft 10
1 (as shown by arrow 103) passes through the outer wall 105 of the fluid handling device 107, such as a valve, pump, etc., enters the container device or packing box 109 through the first opening 111, passes through the packing box 109, and enters the packing box 109. It exits the packing box 109 through the second opening 113. Packing box 109 contains a packing 115 typically made of a conventional flexible graphite packing material in the form of a molded or die cut seal ring 116 as shown. A suitable flexible graphite material is available under the name Graphoil from Union Medium Carbide Corporation of Danbury, CT. An annular end ring 117 is disposed about the axis between the packing material 115 and each of the openings 111, 113. The material of end ring 117 is the flexible graphite/amorphous carbon composite of the present invention.

A compression device, shown here as a threaded gland nut 119, compresses the packing material 115 to tighten the packing material 1.
15 is threaded downward to fit into the interior space of packing box 109 not occupied by end ring 117. Compression also forces the surface of the packing material against the surface of the shaft to form a seal 121 against the passage of fluid. The surface of the end ring is the shaft 101
openings 111 and 11 by forcing it against the surface of
3 and the shaft 101, thus preventing extrusion of packing material through the clearance 123. Without the end ring, the flexible graphite packing would push through the clearance, reducing the packing capacity. Furthermore, if the end ring itself is made of flexible graphite without an amorphous carbon phase, the end ring will also tend to extrude through the clearance.

The dimensions of the endrings of the present invention are generally the same as prior art endrings made, for example, from braided materials and depend on the equipment and the intended packing size.

Generally, the end ring has an annular shape and the inner diameter corresponds to the diameter of the shaft.

As mentioned above, the advantageous properties of the end rings of the present invention are:
The objective is to present the moving shaft with a hard, non-abrasive surface that cleans and polishes the shaft as it moves through the packing.

In some applications it may be desirable to increase this polishing effect.

This can be accomplished by adding a small amount of ceramic material to the flexible graphite and binder mixture. The ceramic material is preferably added in an amount of about 2-30% by weight relative to the weight of the mixture. Ceramic materials are
Powdered ceramics such as refractory oxides, boron nitride, silicon nitride, titanium diboride, etc. can be blended with flexible graphite particles and then added by blending the ceramic/graphite particle mixture with a binder material. Optionally, the flexible graphite particles may be blended with liquid sodium silicate and then reacted with carbon dioxide to leave a solid ceramic layer on the surface of the flexible graphite particles.

EXAMPLES In the following examples, composites of the invention were prepared using the following method.

A crusher and hammer mill are used to grind a flexible graphite sheet available from Union Carbide Corporation under the name Graphoil. Table A below shows the particle size distribution of typical ground flexible graphite used in the examples.

Table A Particle size distribution of flexible graphite Particle size (Tyler Mash) (11m)
(Weight%) > 20 > 0.84
1 0.020~35 0.420
~0.841 0.735~65 0.
210~0.420 19.565~100
0.149~0.21,0 24.5100~
200 0.074~0.149 35.7<
200 <0.074 1
．． 9.6 Phenol thermoplastic is blended with flexible graphite particles in a Hobart TS mixer. The resin is manufactured by Borden Chemical Company under the trade name 5C-1.
Available at 008. Prior to blending, the resin is diluted to 50% by volume with isopropyl alcohol to facilitate dispersion of the resin into the flexible graphite particles.

The blended mixture was then heated in a fume hood for 1 hour.
Leave for 6-48 hours to evaporate the isopropyl alcohol. If the mixture is not intended to be used all at once, it should be stored in a 0°C freezer.

The mixture is prepared in a suitably sized die to a density of about 11
Form by compacting to 0 pounds per cubic foot. The molded article is then cured by heating from 30° C. to 130° C. at a rate of 6° C./hr and held at 130° C. for 1 hour to cure the resin in the molded article. After curing, the resin in the article is carbonized by heating from 50°C to 525°C at 30°C/hr in a nitrogen atmosphere and holding at 525°C for 30 minutes. After cooling, the resulting composite is ready for use. The density of the composite molding is approximately 100 pounds per cubic foot.

EXAMPLE I Tests were conducted on the end ring of the present invention in the packing of the conventional valve seal shown in FIG.

The composite ring of the present invention was manufactured in the above method by blending 80% by weight of flexible graphite particles with 20% by weight of phenolic resin based on the total ff1m.

The approximate dimensions of the ring are 1 inch (approximately 25.4 m) in outer diameter.
, 1/2 inch inner diameter (approximately 12.7 shafts), and 1/2 inch thick
It was 4 inches (approximately 6.35 inches).

The end ring was installed into the valve sealing system as shown using a die cut flexible graphite ring as seal ring 116.

The valve was of a reciprocating type. The valve stem holds the valve at 700'F.
It was circulated through the packing by opening and closing continuously under a pressure of 350 psi at a temperature of (approximately 371° C.). The valve was cycled for 328,000 cycles (this is the standard life of a valve without ring failure). In comparison, the average life without failure of a packing system using braided graphite fiber end rings or die cut flexible graphite seal rings under similar conditions is about 100,000 cycles.

Example ■ A comparative test was conducted on thrust bearing rings for ball valves. Comparative flexible graphite die-molded rings and composite rings of the present invention were made.

The approximate dimensions of the ring are 578 inches outside diameter (approximately 15.9 inches)
It had an inner diameter of 378 inches (approximately 9.5 mm), and a thickness of 716 inches (approximately 1.59 mm). Each thrust ring to be tested was constructed by first placing a flexible graphite seal ring on the mandrel of the ball, placing the thrust ring on the mandrel over the seal ring, and tightening the gland nut onto the mandrel to compress the seal and thrust ring. It was placed on a ball valve with a 1 inch (about 25.4 mm) ball.

The composite ring of the present invention has 65ff for the total ff1m.
The method was prepared by blending i% of flexible graphite particles with 35% by weight of phenolic resin.

A comparative flexible graphite ring was molded from flexible graphite sheet to a density of 90 pounds per cubic foot.

This type of ring is currently used commercially in ball valves.

The composite rings of the present invention and comparative rings were tested by continuously cycling the valve stem at room temperature and at slight positive gauge pressure. The cycle was performed by opening the valve 1/4 turn of the mandrel and closing the valve 1/4 turn in the opposite direction. A comparative flexible graphite ring is 5
．． It broke before 000 cycles. The cycle life of the composite ring of the present invention was approximately 20,000 cycles (which is the standard life of the valve itself).

Although the invention has been described with reference to a particular embodiment and example thereof, it is understood that many modifications may be made without departing from the scope and spirit of the invention, and that the invention may be modified in any way without departing from the spirit of the invention. It will be recognized by those skilled in the art that it covers changes and modifications.

[Brief explanation of the drawing]

The figure is a sectional view of a packing box incorporating the end seal of the present invention. DESCRIPTION OF SYMBOLS 101... Shaft, 105... Outer wall, 107... Fluid handling device, 109... Packing box, 111... First opening, 113... Second opening, 115... Packing , 116... Seal ring, 117... End ring, 119... Grand nut, 123... Clearance.

Claims (1)

Claims: 1. A composite comprising particles of flexible graphite and an amorphous carbon phase bonding the flexible graphite particles together. 2. The amorphous carbon phase is 1% by weight of the composite based on the total weight.
A composite according to claim 1, comprising ~50% by weight. 3. Amorphous carbon phase is 8% by weight of the composite based on the total weight
2. A composite according to claim 1, comprising ~33% by weight. 4. The density of the composite is between 50 lb/ft3 and 13
2. The composite of claim 1, wherein the composite has a weight of 0 pounds per cubic foot. 5. The density of the composite is between 80 lb/ft and 10
2. The composite of claim 1, wherein the composite has a weight of 0 pounds per cubic foot. 6. The composite of claim 1, wherein the compressibility of the composite is between 5% and 11% as measured by ASTM F-36 test method. 7. Claim 1, wherein the composite also includes trace amounts of ceramic material.
The complex described in. 8. Ceramic material is 2% by weight based on the weight of the composite.
8. A composite according to claim 7, wherein the composite is present in an amount of ~30% by weight. 9. (a) Container device arranged on the wall and around the shaft and around an opening in the wall; (b) Elastic packing material placed in the container device around the shaft; (c) Shaft and opening An end ring located within the container device and adjacent to the packing material around the axis on the clearance between the edges of the end ring (the end ring binds the particles of flexible graphite and the flexible graphite particles together (d) compressing the end ring and packing material in the direction of the shaft centerline to conform the packing material to the interior space of the container device and the shape of the shaft to provide a seal and to ensure that the end ring is when the shaft passes through the opening in the wall, comprising a compression device for blocking the clearance between the shaft and the edge of the opening to prevent extrusion of packing material through the clearance; A seal suitable for preventing fluid leakage through the clearance between the moving axis and the edge of the opening. 10. The seal of claim 9, wherein the amorphous carbon phase of the end ring accounts for 1% to 50% by weight of the endring relative to the weight of the endring. 11. The seal of claim 9, wherein the amorphous carbon phase of the end ring accounts for 8% to 35% by weight of the endring relative to the weight of the endring. 12. The seal of claim 9, wherein the end ring has a density of between 50 pounds per cubic foot and 130 pounds per cubic foot. 13. The seal of claim 9, wherein the end ring has a density of between 80 pounds per cubic foot and 100 pounds per cubic foot. 14. The compressibility of the end ring is 5% to 11%.
A seal according to claim 9. 15. The end ring also contains trace amounts of ceramic material.
A seal according to claim 9. 16. The seal of claim 15, wherein the ceramic material in the end ring is present in an amount of 2% to 30% by weight relative to the weight of the endring. 17. The seal of claim 9, wherein the resilient packing material is flexible graphite. 18. The container device has a second opening opposite the opening in the wall, through which the shaft passes through the wall of the container device, and a seal is formed between the shaft and the edge of the second opening. additionally comprising a second end ring disposed within the vessel device about the axis on a clearance between the particles of flexible graphite and the flexible graphite particles together; 10. The seal of claim 9, comprising an amorphous carbon phase. 19. In producing a composite consisting of particles of flexible graphite and an amorphous carbon phase bonding together the particles of flexible graphite, (a) a flexible graphite molding is pulverized to form flexible graphite; (b) Mixing particles of flexible graphite with an organic binder to provide particles of 40-99% by weight of flexible graphite particles and 1 binder;
(c) forming the mixture into a cohesive molding; (d) heating the molding to a temperature that carbonizes the binder. 20, the mixture has at least 10
20. The method of claim 19, containing % binder by weight. 21. Claim 19, wherein the binder is a liquid thermosetting resin.
The method described in. 22. The method of claim 21, wherein the liquid thermosetting resin is a phenolic resin. 23. The method of claim 19, wherein the mixture contains 10-35% by weight of binder and 65-90% by weight of flexible graphite particles. 24. The method of claim 19, wherein the density of the molded article in 24, (c) is between 55 lbs/ft3 and 135 lbs/ft3. 25. The method of claim 19, wherein the density of the molded article in 25.(c) is between 90 pounds per cubic foot and 100 pounds per cubic foot.